Reconstitution Calculator

Semaglutide Reconstitution Calculator

This semaglutide reconstitution calculator turns your vial size and bacteriostatic water into a concentration and insulin syringe units, so a 5 mg vial mixed with 2 mL is 2.5 mg/mL.

Work out how to mix a semaglutide vial. Enter the vial size and how much bacteriostatic water you plan to add, and this tool returns the concentration, the volume to draw, the insulin syringe units, and how many doses the vial holds. It does the arithmetic only on the figures you supply. It does not choose a dose for you. For what low-dose and microdosing semaglutide actually means, plus the milligram-to-unit arithmetic behind these conversions, see the guide.

For semaglutide pricing and availability in Vietnam, the semaglutide in Vietnam guide covers costs and sourcing separately from the vial arithmetic here.

Vial and water inputs

The pre-filled semaglutide entries demonstrate how the results change with vial content and water volume. These are a placeholder to demonstrate the arithmetic, not a recommended or starting dose. Each field accepts your recorded numbers; the water value must describe the solution being calculated. Disclaimer: educational only, not medical advice.

Total peptide in vial

1 mg30 mg

Bacteriostatic water added

0.5 mL5 mL

Dose per injection

0.05 mg10 mg

Insulin syringe size

Reconstitution result

Concentration

2.5 mg/mL

2500 mcg/mL

Volume per dose

0.2 mL

200 microlitres

Insulin syringe units

20 units

Draw to about the 20-unit mark on a U-100 syringe

Doses per vial

10 doses

Approximate, assuming exact reconstitution

Units assume a U-100 insulin syringe where 1 unit equals 0.01 mL.³ Always cross-check with your supplier's recommended reconstitution volume.

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Semaglutide reconstitution chart for 5 mg, 10 mg and 30 mg vials

The table runs the calculator arithmetic for 5 mg, 10 mg and 30 mg semaglutide vials at 1, 2 and 3 mL of bacteriostatic water. The amounts are round numbers for the math, not doses to take. Units are on a U-100 insulin syringe, where 1 unit is 0.01 mL.³

Vial	BAC water	Concentration	Units for 0.25 mg	Units for 1 mg	mg in 10 units
5 mg	1 mL	5 mg/mL	5 units	20 units	0.5 mg
5 mg	2 mL	2.5 mg/mL	10 units	40 units	0.25 mg
5 mg	3 mL	1.67 mg/mL	15 units	60 units	0.17 mg
10 mg	1 mL	10 mg/mL	2.5 units	10 units	1 mg
10 mg	2 mL	5 mg/mL	5 units	20 units	0.5 mg
10 mg	3 mL	3.33 mg/mL	7.5 units	30 units	0.33 mg
30 mg	1 mL	30 mg/mL	0.8 units	3.3 units	3 mg
30 mg	2 mL	15 mg/mL	1.7 units	6.7 units	1.5 mg
30 mg	3 mL	10 mg/mL	2.5 units	10 units	1 mg

Disclaimer: these are unit conversions, not dose recommendations. Educational only; dose decisions belong with a licensed clinician.

How semaglutide reconstitution works

Semaglutide powder and a pre-filled semaglutide pen start in different forms: the powder requires reconstitution, while the pen already contains a solution. This calculator describes the powder-vial arithmetic, using the general peptide-handling reference for the meaning of reconstitution.⁴ Its water field represents the liquid volume used to calculate concentration. The bacteriostatic water reference describes that diluent,¹ but does not establish instructions for a particular semaglutide product.

For the semaglutide vial entries above, concentration connects the amount in milligrams to the volume and syringe reading:

concentration (mg/mL) = vial mg / water mL

volume per dose (mL) = dose mg / concentration

insulin units = volume per dose mL x 100

Here, U-100 units describe volume: 1 unit equals 0.01 mL.³ The semaglutide content associated with that mark depends on the concentration calculated from your vial and water entries.

Why 2 mL is the default

The 2 mL default gives the semaglutide examples a common starting point for comparing concentrations. The calculator does not know the physical capacity of your vial, so this preset cannot confirm that a volume will fit. It also does not apply to a pre-filled semaglutide pen.

The semaglutide chart shows why one water volume can produce very different syringe readings. A 10 mg vial in 2 mL is 5 mg/mL, so a 0.25 mg amount is only 5 units. The small-measurement warning appears below about 5 units; it describes the calculated reading, not whether that semaglutide amount is suitable. These figures illustrate arithmetic, not a semaglutide dose recommendation.

The editable water field lets the calculation reflect a recorded semaglutide mixture instead of assuming the 2 mL example applies to every vial. Changing water volume updates concentration and draw volume; the vial count still depends on the two milligram entries.

How to reconstitute a semaglutide vial

Swab both stoppers. Wipe the rubber stopper of the peptide vial and the bacteriostatic water vial with an alcohol swab and let them dry.
Draw the water. Draw the bacteriostatic water volume the calculator shows, 2 mL by default, into a syringe.
Inject down the wall. Insert the needle at a slight angle so the water runs down the inside wall of the vial rather than directly onto the powder. This reduces foaming.
Swirl, do not shake. Inject the water slowly. Do not shake the vial. Swirl gently until the solution is clear.
Label the vial. Label the vial with the reconstitution date and the concentration in mg per mL.
Refrigerate. Refrigerate the reconstituted vial. Do not freeze it. Follow the supplier storage instructions.

The bacteriostatic water for this step is available from Peptara Labs, our supply partner, in 3, 5 and 10 mL bottles. The same mixing steps and math apply to a related GLP-1 research peptide, such as the vials on Peptara's tirzepatide page.

Worked examples

These semaglutide examples compare two vial strengths with the same water volume. They are illustrations of the math, not doses to take. Neither example sets a personal semaglutide target.

Example A: 5 mg vial, 2 mL water

Math illustration, not a dose to take. For this semaglutide vial, 5 / 2 = 2.5 mg/mL. A 0.5 mg amount gives 0.5 / 2.5 = 0.2 mL, which is 20 units on a U-100 syringe. The vial contains 5 / 0.5 = 10 illustrative draws.

Example B: 10 mg vial, 2 mL water

Math illustration, not a dose to take. The second semaglutide vial gives 10 / 2 = 5 mg/mL. A 0.25 mg amount gives 0.25 / 5 = 0.05 mL, which is 5 units on a U-100 syringe. The vial contains 10 / 0.25 = 40 illustrative draws.

Disclaimer: this is educational only, individual protocols vary, and dose decisions belong with a licensed clinician.

The two semaglutide examples share a 2 mL water volume but have different concentrations. A unit reading copied from another vial therefore cannot identify the semaglutide amount in yours.

Reading the insulin syringe

This semaglutide calculator expresses volume on a U-100 scale. That scale measures liquid volume, while milligrams describe the semaglutide amount:

1 unit = 0.01 mL

100 units = 1 mL = full 1 mL barrel

The semaglutide examples above translate 0.2 mL to 20 units and 0.05 mL to 5 units. Selecting a 0.3 mL, 0.5 mL, or 1.0 mL barrel changes the capacity check, but does not change the semaglutide concentration or the U-100 conversion.

How the water volume changes the draw

Compare the water columns in the semaglutide chart: each row starts with the stated vial content, and dilution changes how much of that content is in each millilitre. A 5 mg semaglutide vial with 1 mL has twice the concentration of the same vial with 2 mL, so an equal milligram amount occupies half the volume.

Less water (1 mL)

The 1 mL column shows the most concentrated semaglutide mixture in this comparison, with the smallest volume for an equal milligram amount.

2 mL, the default

The 2 mL column matches the starting water entry used in the semaglutide examples above; it is not a product-specific mixing instruction.

More water (3 mL)

The 3 mL column spreads the same semaglutide vial content through more liquid, so an equal milligram amount corresponds to a larger volume.

If you want the same concentration math without a compound preset, the general peptide reconstitution calculator handles any vial, the bac water vs sterile water explainer covers which diluent a re-entered vial is built for, and the beginner injection guide walks through the mixing and measuring steps in plain terms.

Safety notes before you mix or draw

The FDA has reported adverse events, some requiring hospitalisation, from dosing errors with compounded semaglutide, where people measured and injected the wrong amount.⁵ Before you draw, check that the vial and the dose are both in mg and that your syringe is U-100. An unexpected semaglutide result needs review with a clinician before it is used.

The Wegovy (semaglutide) prescribing label lists nausea, diarrhea, vomiting and constipation among the most common side effects.⁶ This calculator cannot assess side effects or determine whether a semaglutide product is safe for an individual.

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Frequently asked questions

How much BAC water do I add to a semaglutide vial?

For a semaglutide powder vial, the water entry determines the calculated concentration; a pre-filled semaglutide pen already contains a solution. The 2 mL starting value is an arithmetic example, not a mixing instruction for your product. The chart compares 1 mL, 2 mL and 3 mL so you can see how the same vial amount produces different unit readings.

How much bacteriostatic water do I mix with 10 mg of semaglutide?

2 mL is the default here for a 10 mg semaglutide vial, and it gives 5 mg/mL, so every 10 units on a U-100 insulin syringe holds 0.5 mg. With 1 mL the same vial is 10 mg/mL (1 mg per 10 units), and with 3 mL it is about 3.33 mg/mL (about 0.33 mg per 10 units). These are unit conversions, not a recommended dose. Disclaimer: educational only, and dose decisions belong with a licensed clinician.

How much bacteriostatic water do I mix with 30 mg of semaglutide?

2 mL is the default here, and it makes a 30 mg semaglutide vial 15 mg/mL, so every 10 units on a U-100 insulin syringe holds 1.5 mg. With 3 mL the same vial is 10 mg/mL (1 mg per 10 units), which spreads small amounts over a larger, easier draw if your vial holds that volume. Even at 3 mL, any amount under 0.5 mg lands under 5 units, where a misread of one unit matters most. Disclaimer: these are unit conversions, not a recommended dose, and dose decisions belong with a licensed clinician.

How many units is a 2mg semaglutide dose?

It depends entirely on the concentration you mixed. As a worked example, a 10 mg vial reconstituted with 2 mL is 5 mg/mL, so a 2 mg amount is 0.4 mL, which is 40 units on a U-100 insulin syringe. That is arithmetic on the numbers you enter, not a recommended dose. Disclaimer: this is educational only, individual protocols vary, and dose decisions belong with a licensed clinician.

How many doses does a semaglutide vial make?

For semaglutide, the doses-per-vial result divides the entered vial content by the entered amount for each draw. As a worked example, a 5 mg vial at a 0.5 mg amount is 10 draws, and a 10 mg vial at 0.25 mg is 40 draws. That semaglutide vial count assumes exact reconstitution and does not account for losses. Disclaimer: educational only.

Can I use more or less water than 2 mL?

The semaglutide water field accepts volumes above or below its 2 mL starting value. For the same semaglutide amount, a more dilute solution gives a larger calculated volume; a more concentrated solution gives a smaller one. Changing this entry does not change the vial content or establish which volume suits a particular product.

What is the difference between BAC water and sterile water?

Bacteriostatic water contains a preservative; sterile water for injection has none. The semaglutide concentration calculation cannot establish whether either diluent is suitable for a particular vial, or how long the resulting solution can be stored. A pre-filled semaglutide pen already contains its liquid formulation and falls outside this mixing calculator.

Does this calculator tell me what dose to take?

No. The semaglutide amount is an input you supply, and the outputs describe only the resulting concentration, volume, syringe reading and vial count. A calculated result cannot select a semaglutide dose or assess whether it is appropriate for you; those decisions belong with a licensed clinician. For what semaglutide costs in Vietnam and how people source it, read the semaglutide in Vietnam guide instead.

This calculator covers semaglutide math only, and the same arithmetic works for retatrutide, a newer research peptide in the same GLP-1 family that our supply partner lists on Peptara's retatrutide page.

This is harm reduction education, not medical advice

This semaglutide tool provides educational arithmetic from the numbers entered. It cannot choose a dose, validate a product or replace a clinician who knows your medical history. Product-specific instructions and clinical decisions remain outside what a concentration calculation can establish.